In refining chemical and petrochemical applications, conventional scallops are used in radial flow reactors and function as conduits through which gas, vapor or liquids (hereinafter, referred to as “G-V-L”) flow inside the reactor vessel. Scallops are typically formed as elongated, tube-shaped conduits of various geometry, typically having a cross-sectional “D” shape (although other shapes are also used), through which G-V-L flow radially in an inward or outward direction relative to the vessel. The scallops are typically formed of various metal constructions, sometimes having openings on a surface thereof to allow the G-V-L to flow freely through the surface of the scallop, as well as along the length of the scallop. When the G-V-L flow through the scallop and escape through the openings on the surface, they come into contact with catalyst particles contained within an adjacent catalyst bed, thus causing a reaction to take place. In use, the scallops are placed adjacent to one another along the inner circumference of the wall of the reaction vessel.
One common problem with such scallop designs is that they are prone to crushing when in use. Specifically, G-V-L are passed through the scallops at elevated temperatures, pressures and flow rates in order to effect the reaction. The elevated temperature, pressures and flow rate of the G-V-L cause the catalyst bed to heat quickly and expand, thereby increasing the risk of crushing of the adjacent scallops. Some additional causes of scallop crushing include, for example, catalyst plugging, catalyst flow interruptions, material fatigue, corrosion, and other factors. When the scallops are crushed, the G-V-L flow is restricted in the crushed area, thus reducing or preventing the G-V-L from making contact with the catalyst. When this happens, the reaction cannot take place, or is detrimentally reduced, in the crushed zone and the reaction efficiency of the vessel is thus reduced.
Methods of minimizing this crushing effect have been developed in the art, including the use of scallop support structures. However, even such support structures have a tendency of being crushed under the operating conditions of the reaction vessel. Moreover, such structures only support the scallop in the area where they make direct contact with the surface of the scallop. As such, collapse of the scallop in the unsupported areas is still a problem.
Accordingly, an improved scallop support structure is needed that reduces the crushing effect of the scallop and supports the entire scallop structure throughout its lifetime of use in a reactor vessel.